The present invention relates to an endoscope comprising an inserting portion insertable into, for example, a body cavity of a subject, an interior of a machine or the like, to perform observation and, more particularly, to an operating mechanism for a bendable section of the inserting portion.
A usual, conventional endoscope comprises an operating body and an inserting portion extending therefrom, in which the inserting portion has a distal end section formed into a bendable section. An angularly movable member such as a pulley or the like is mounted, within the operating body, on a shaft for angular movement therewith around an axis thereof. An operating member such as a lever is connected to an end of the shaft which extends outwardly from the operating body. The angularly movable member is operatively connected to a distal end of the bendable section through a pair of operating wire sections. After insertion of the inserting portion of the endoscope into, for example, a body cavity of a subject by an operator or an operating surgeon, he turns the operating lever to angularly move the angularly movable member around the axis of the shaft. The angular movement of the angularly movable member is transmitted to the bendable section through the operating wire sections to bend the bendable section toward any desired direction.
The construction as described above is somewhat disadvantageous in that as the bending angle of the bendable section increases, the reaction force from the bendable section increases and, therefore, great force is required for the operating surgeon to operate the operating lever to angularly move the angularly movable member, to thereby result in reduction in the operability.
As disclosed in Japanese Patent Publication No. 56-13455 and Japanese Utility Model Application Laid-Open No. 58-160002, an arrangement has been proposed in which an electric motor is utilized as a power source. The electric motor is incorporated into the operating body and is operatively connected to the angularly movable member for angularly moving the same around the axis of the shaft.
With the construction as described above, the operability is reduced, because the incorporation of the electric motor into the operating body increases the weight thereof. In addition, in the event that the failure of electric power supply occurs after the inserting portion has been inserted into the body cavity of the subject and the bendable section has been bent to a desired angle, it is no longer possible to withdraw the inserting portion out of the cavity of the subject, because it is impossible to release the bent condition of the bendable section.